null pointer exception in radio Button

Question

I have some code in which i use radio Button for selection purpose.but i get en error while click on button. can anyone help me to solve this. My code is as below...

Error Code

2020-03-13 07:35:36.577 9611-9611/com.hpcreation.hanumanchalisa E/id: -12020-03-13 07:35:36.585 9611-9611/com.hpcreation.hanumanchalisa E/AndroidRuntime: FATAL EXCEPTION: main
Process: com.hpcreation.hanumanchalisa, PID: 9611
java.lang.NullPointerException: Attempt to invoke virtual method 'java.lang.CharSequence android.widget.RadioButton.getText()' on a null object reference
    at com.hpcreation.hanumanchalisa.LanguageChooserActivity.startChalisa(LanguageChooserActivity.java:40)
    at com.hpcreation.hanumanchalisa.LanguageChooserActivity$1.onClick(LanguageChooserActivity.java:31)
    at android.view.View.performClick(View.java:6300)
    at android.view.View$PerformClick.run(View.java:24941)
    at android.os.Handler.handleCallback(Handler.java:790)
    at android.os.Handler.dispatchMessage(Handler.java:99)
    at android.os.Looper.loop(Looper.java:164)
    at android.app.ActivityThread.main(ActivityThread.java:6523)
    at java.lang.reflect.Method.invoke(Native Method)
    at com.android.internal.os.RuntimeInit$MethodAndArgsCaller.run(RuntimeInit.java:438)
    at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:857)

My Button Click Event

startRead.setOnClickListener(new View.OnClickListener() {
@Override
public void onClick(View v) {
    startChalisa();
}});

StartChalisa Method is as :

public void startChalisa() {
int selectedID = group.getCheckedRadioButtonId();
Log.e("id", String.valueOf(selectedID));
RadioButton radioButton = findViewById(selectedID);
if (radioButton.getText() == null) {
    Toast.makeText(this, "selectLanguageFirst", Toast.LENGTH_SHORT).show();
} else {
    switch (radioButton.getText().toString()) {
        case "Hindi":
            languageOP(this, new MainActivity(), "Hindi");
            Toast.makeText(this, "Hindi", Toast.LENGTH_SHORT).show();
            break;
        case "English":
            languageOP(this, new MainActivity(), "English");
            Toast.makeText(this, "English", Toast.LENGTH_SHORT).show();
            break;
        default:
            break;
    }
}}

LangugeOP method is as:

void languageOP(Context context, MainActivity mainActivity, String choice) {
Intent intent = new Intent(context, mainActivity.getClass()).putExtra("choice", choice);
startActivity(intent);}

Answer 1

I suspect that the problem is here:

 int selectedID = group.getCheckedRadioButtonId(); RadioButton radioButton = findViewById(selectedID); if (radioButton.getText() == null) { // ... }

It looks like you're trying to handle the case where no radio button has yet been selected, but not going about it the right way.

getCheckedRadioButtonId() returns -1 when nothing has been selected. So you could check that immediately:

int selectedID = group.getCheckedRadioButtonId();
if (selectedID == -1) {
    // ...
}

Or, if you want to work with the view specifically, you could check if the view is null (not if its text is null):

int selectedID = group.getCheckedRadioButtonId();
RadioButton radioButton = findViewById(selectedID);
if (radioButton == null) {
    // ...
}

Answer 2

我认为你应该尝试((RadioButton) group.getChildAt(checkedId))来找到你的 RadioButton